[support] I am looking for suggestions on how to implement banner ads utilizing google type ads (or someone else)

In order to help pay for our drupal 6 website we need to be able to derive some revenue from banner ads. I am looking for suggestions on how to implement banner ads utilizing google type ads (or someone else) so that the ads display within a predefined rectangle and if the users clicks on an ad (which takes them to a new tab/page) it gives our company some revenue. john